In the densely wooded Santa Cruz Mountains where last week”s wildfire torched 4,270 acres and 31 homes, the notion of deliberately burning brush to get rid of it strikes some as an invitation to disaster.

But it happens every winter and spring, with local fire officials signing off on dozens of debris-burning permits and trusting property owners to control the flames.

It may be weeks before fire officials say what sparked the Summit Fire, Santa Cruz County”s largest in a century. But the possibility that debris burning ignited the blaze — which fire investigators have not ruled out — has left some residents questioning oversight and regulation of the longstanding practice, which ironically aims to cut down on fire risk by clearing away excess fuel.

“This is just insane,” said Rene Rylander, who has lived on Old Santa Cruz Highway near the summit in Los Gatos for 20 years. “I just find it really hard to believe the fire department, given the severity and potential impact burning can have, is still issuing permits.”

The California Department of Forestry and Fire Protection cut the open burning season in Santa Cruz County two weeks short in April after about 30 debris fires — at least a half dozen of them in the mountains — “escaped” and ignited surrounding brush dried by a rainless spring. One of those scorched three acres before it was extinguished.

On the Santa Clara County side of Summit Road, a man who owns acreage in the area where fire officials believe last week”s wildfire started acknowledged he was burning brush there seven weeks earlier. He said he had a permit.

Cal Fire officials would not confirm that or open their records to inspection, saying they require a formal Public Records Act request through their Sacramento headquarters. They have yet to respond to such a request made by MediaNews this week; the act requires a response within 10 days.

Brush-burning regulations vary in the Santa Cruz Mountains because two counties and two air quality districts collide at Summit Road.

On the Santa Cruz County side to the south, where the slopes are bathed in cool, foggy ocean breezes and thick with redwood groves over moist fern undergrowth, property owners can generally burn small brush piles from December through April. Firefighters have long considered the wildfire risk so low in the damp hillsides that they dubbed the Santa Cruz region “asbestos county.”

Because the sea breezes tend to disperse pollution before it becomes a health hazard, the Monterey Bay Unified Air Pollution Control District does not forbid backyard debris burning, although some cities do and fire officials have authority to suspend it for safety reasons.

Residents who want to burn a small pile of brush during the wet season need only fill out a one-page form at the local fire station with their name, address and the location of the proposed burn. The person doing the burning must stand by with a shovel and hose and may be held liable for firefighting costs if the flames get out of control.

The Santa Clara County side of the mountains fall under Bay Area Air Quality Management District regulations, which generally prohibit open burning. Because of that, a number of debris-chipping programs are available to mountain residents above Los Gatos so they can dispose of brush that poses a wildfire hazard without burning it. Fire Safe Councils, nonprofits established by Cal Fire that operate on federal grants, offer the service for free.

But the Bay Area air district”s 10 pages of open-burning regulations allow burning under some conditions. Commercial agricultural operations, including vineyards, may obtain permits to burn brush. Property owners also may obtain a permit to burn brush that poses a wildfire hazard if it is a substantial amount — more than five cubic yards — and there are no other practical means of disposing it.

The air district allows burning only on specified days when atmospheric conditions allow for dispersal of the smoke, and the district requires notification by the permit holder. District officials would not say whether they were notified of any burning in the summit area this year, insisting first on a formal public records request, which they have yet to answer.

Andrew Napell, who owns land in the area where firefighters believe the Summit fire started, told MediaNews on Tuesday that he had a permit to burn. He said “all land clearing and hazard reduction fire activity on my Mount Madonna property ceased on April 4,” adding that he is working with “arson investigators” and been told not to comment further.

Neighbors have suspected that dry, gusty northeasterly winds that howled across the summit before dawn May 22 somehow stirred up embers smoldering from the debris burn almost two months earlier and ignited the wildfire.

Fire officials won”t comment on that or any of the other theories wafting like smoke in the aftermath of the wildfire. The stakes are high, with the costs of fighting the fire estimated at $12.2 million, and a premature statement could jeopardize the case. For now, they”ll say only that the cause remains under investigation.

But fire officials said it”s not inconceivable that embers from a debris burn could smolder for weeks. And although they declared the wildfire fully controlled Friday, they also expect spots within its perimeter to remain hot; firefighters will be standing watch throughout the summer to douse any flare-ups.

Fire officials say debris burning has not historically been a problem.

“We issue thousands of burn permits on an annual basis,” Capt. Matt Streck of Cal Fire in Santa Clara County said. “The vast majority of the burning is safe. My experience has been that if people follow the rules they agree to on their permit, we don”t have problems.”

He and other fire officials said debris chipping can be costly and inconvenient for some, and impractical in some remote areas. The Santa Clara County Fire Safe Council”s chipping program, for instance, costs $100,000 a year and is paid for by grants.

But Streck acknowledged that “it”s not unusual at the beginning of fire season to have a couple of escaped debris burns.”

The conflicting jurisdictional rules at the summit also create some tension among residents.

“Right across the street on Summit Road, they can burn, and they do it constantly because they”re on the Santa Cruz side,” said Mona Raby, office manager of the Redwood Estates Services Association, which runs a debris chipping program for residents. “They”ll burn right across the street from a forest, and there”s nothing we can do about it.”

Alex Leman, chief of the Loma Prieta Fire and Rescue volunteer fire unit, which straddles the county line, said he hasn”t yet detected a groundswell among mountain residents for reconsidering debris-burning rules, because many appreciate the convenience.